Electrical selector.



. E. A. PALLBR." ELECTRICAL SELECTOR. APPLfOATI ON FILED APR. 8, 1904.

Patented July 6, 1909.

3 SHEETS-SHEET l.

V I f Z 12 witnesses I M .7722767220] I B. A. FALLER. ELECTRICAL SELECTOR.

APPLIOATION FILED APR.8,1904. 927,455. Patented July 6, 1909; I a sun 113m 2.

36 llll ll lll llllllll'llll illnesses Jnventor w 4L7 a E. A. FALLER.

ELECTRICAL SELEGTOR.

APPLICATION FILED APR.8,1904.

Patented July 6,1909. 3 SHEETtF-SHEET 3.

witnesses To all whom a m, cm..-

UNITED STATES PATENT OFFICE.-

ERNEST A. FALLER, OF NEW -YORK, N. Y., ASSIGNOR'TO THE NORTH ELECTRIC COMPANY,

p OF CLEVELAND, OHIO, A CORPORATION OF'OHIO.

ELECTRICAL SELECTOR.

Patented July 6, 1969.

Application filed April 8, 1904. Serial No. 202,262.

-Be it known that I, ERNEST AUGUST FAL- LER, a'citizen of the German Empire, residing in New York, in the county of New York and State of New York, have invented a new and useful Electrical Selector, of which the following is a specification.

The present invention relates to apparatus or devices forestablishing a regular order of electrical actuations caused by. an entirely irregular order-of initiating acts.

One mode of application of the present iiivention is, for instance, in connection with telephone systems, in which the signals of the calling subscribers are received at the exchange in an arbitrary irregular order, while it is desirable to arrange the samein a regular order or sequence for the purpose of establishing connection with the called subscribers.

For this purpose the invention consists of the construction and arrangement of parts, mechanical and electrical, and of the electrical circuits hereinafter set forth, which in a general-way com rise initiating or calling devices at the sen er stations, actuating or translating devlces, intermediary circuit establishing means and controlling devices for the latter. All the devices with the exce tion of the sending apparatus are preferab y located at a central station, such as a telephone exchange, the sending apparatus however, may be located at places distant from the central station.

It will be seen that the apparatus herein described and illustrated is adapted to a decimal system. i

An entire number of one hundred lines entering a central station is divided into .groups of ten terminals. Each group of ten terminals of the isolator, is represented at the group selector by one row of=contact points and controlled by one group selector magnet.

The function of one of these magnets is to place, for the time being, the entire central station under the control of one group of ten of the terminals. has been selected, the individual selector selects one terminal in the group and. for the time being, places the entire central station under the control of this individual terminal? The individual translating device is now operated, whcreafter the entire system reverts to common use.

It is old in the art to select a line by means of a traveling contact findingxastationary When this group of ten' contact which lattei is in a condition other than normal, but in this case the traveling contact was caused to stop and t6 interrupt its movement by its own act of finding a line. 7 Devices ,for t is general purpose are known in the art as ine finders and are em- U. S. Patent No. 279,023, patented June =5, 1883, and. in automatic telephone systems, such as described and claimed in the U. S. Patent No. 686,892, patented November-19, 1901. One o'f'the essential differences between devices of this character and the present invention consists in the fact that in the former the traveling contact forms part of a circuit over which the controlling electromagnet is energized, whichis not the case in the present invention. If such a line finder is intended for one hundred lines, its speedcannot be much more than fifteen 'revolu tions per minute, for the reason that the com tact between the traveling contact and the stationary contact must be of sufficient duration to enable the controlling electro-magnet to attract its armature before the contact is again broken.

It is obvious that the time of operation including the interval between two successive operations may vary from one twentieth of one second to four seconds, averaging a consumption of time of two seconds per operation. In the present invention, however, in which the traveling contact does not form part of a circuit over which the controlling magnet is energized, this space of time is eliminated, as the actuationoi' the controlling magnet is not depending upon the traveling contact maker and the contacts are entirely at rest during the time of performing their useful function. i

It will be seen, that in the present inven tion, the speed of operation of the normally rotating contact maker is only limited by the mechanical strength of the cooperating parts and the required safety. In the apparatus illustrated, the speed of the normally rotating trailer arm is 400 revolutions per minute, a speed entirely impracticable in any of the machines heretofore in use. In the present invention, the stopping of the traveling contact is not caused by its own act of finding a line, but by a prior operation beyond the control of the traveling contact and independent thereo'l'. This is thought to be ployed for instance, in electrical gas cut outs such as the automatlc electric clrcuit'opener,

selecting one of the components of the sebroadly new, as is also the herein described division of an entire selecting act into more than one specific selecting acts, one of them selecting one group out of a plurality of groups of circuits and rendering the other groups for a time inoperative, and the other le'cted group and rendering for a time all other components of said group inoperative. In this manner the final circuit is selected by what might be termed a process of elimination. It is obvious, of course, that this arrangement is not limited to the use of a deci mal system nor to only two selecting acts,

- but any desired division into groups may be applied and any desired number of selecting acts may be resorted to'without departing from the intended spirit and scope of the present invention.

In the drawings accompanying the present application for Letters Patent and forming a part thereof, Figures 1 and 2 are diagram- 'matic views illustrating the circuit selecting devices and their connections; Fig. 3 is a detailed diagrammatic view of the complete circuit of one line when continued to its translating device, and Fig. 4 is a detailed view of a mechanical device at the central station capable of being acted upon by an individual translating device belonging to a The entire central apparatus may'b'e divided into four parts. The isolator, the group selector, the individual selector and the translator or actuator.

The isolator consists of a series of terminals, one for each of the lines ending at the central station. The terminals are preferably in the shape of clips2 and are arranged in groups of ten, each terminal in the group connected to one of the lines leading into the station, and each group having an eleventh clip 4 connected to battery and ground'as hereinafter more fully will appear.

The isolator com rises on a suitable frame, the isolator bar 6, s idably supported by pins or bolts and provided witha series of isolator blades 7 secured to the bar 6 and resting on non-conducting material so that the blades 7 are capable of normally bridgin all eleven clips 2 forming one group. The isolator bar 6, 18 ca able of lateral movement by means of a bellbrank lever 8 held under tension of a spring 9 by a detent 10 which latter forms t e armature of an isolator magnet 11 connected by a conductor 12 to a battery ring 18 0f the group selector and to battery and ground. Each of the isolator clips 2 is connected by a conductor 3 to a contact point 19 on the group selector of the apparatus. The contact points belonging to the same group are arranged in radial lines around the axis of the shaft 20. Each group of contact points 19 is provided with a group selector magnet 13 connected by means of a conductor 5 to the eleventh or ground clip 4 of the'isolator and on the other hand by a second conductor to a battery ring 17 which in turn is connected by conductor 45 to the main switch 35 and through battery 36 to ground. Each one of the group selector magnets 13 provided with an armature 14 acting. asa detent for a stop 15, the. latter capable of dropping into the path of a trailer arm 21, sothat this trailer arm 21 which is normally rotating on the shaft 20 to which it is frictionally secured, may stop on that row of contact points 19 which, belongs to the energized group selector magnet 13.

In each row of contact pins 19 in the group selector,'ten of the contact pins are connected to the corresponding clips 2 of the isolatormaking contact with the contact points 19,

and the innermost trailer brush of this series capable of making contact with the contact oints 26, and a second series 24 of contact rushes arranged to slide upon a corresponding series of conducting rings 25, each of the conducting rings connecte by a conductor 29 to the individual selector as hereinafter will be more fully described. The brushes of the outer series 23 and the inner series 24 are connected in pairs, respectively, the outermost brush of the series 23 to the innermost brush of theseries 24 and so on. The brush capable of making contact with the inner most contact oints 26 ofthe rows of contact points 19 of t e group selector is connected to the outermost contact brush of the inner series 24 which glides on a ring 46, the latter being connected by means of the conductor 47 to ground. Each of'the stops 1.5is ar ranged to make contac't with contact points 16, the stop 15 is electrically connected to the battery ring 17, to which also, as h'ereinbe: fore stated, the magnet 13 is connected and thecontact point 15 is connectedto the outer ring 18 of the group selector and by means of a conductor 12 through the isolator magnet '11 to ground.

The construction of the individual selector Fig. 2 of the drawings, is verysimilar to the construction of the group selector. This individual selector consists of a series of magnets 30, each of Whichis connected by means of a conductor 29 to one of the rings 25 of the group selector Fig. 1, the other Wire of the magnet leading to a battery ring 33 whichlby means of a conductor 34 is connected to the main switch 35 and through battery 36 to ground. 7 Each of the magnets 30 is pro.- vided with an armature 31 acting as a detent amass nected by meansof a conductor 42 to the main switch 35 and through battery 36 to ground. pable of making contact in succession with contact points 43, each of which is connected by means of a conductor 44 to one of a number of translating devices 28 of the actuating device. Both-trailer arms 21 and 38 are driven by a common power-device and mayfrictionall be secured to constantly rotating separate s afts 20 and 37 ,'or to one common shaft. Each selector may also be provided with a dial having numbers or other char'actersand each trailer arm with an indicator, such as the hand 22,"Fig. 1, so as to indicate the group on the selector and the component of this group on the individual selector, which for the time being control the operation of the central station.

From the foregoing description, itwill be seen that the lines or circuits entering the isolator from the outside, are divided into groups, and that the normal course of these circuits is from the clips 2 and 4 of eachgroup through the respective magnets 13, to ground through battery; the magnet 13 of each group being common to all the circuits of that group. It will further be seen that the wires 3 constitute parts of circuits branching at the clips 2 in groups from the respective groups of grounded circuits entering said clips; that these branch circuits are normally open; that they may be partially closed in grou s b the normally rotating contact brus ice 0 the group selector; that this selector includes primary controlling devices (the magnets 13 and their detents) one for each of the groups of main circuits entering the isolator: that a secondary circuit closing device comprising the individual selector acts to com letel close any one of the partially closed ranc 1 circuits, and that all the circuits entering the apparatus, save the one selected, are rendered temporarily inoperative after the selection of said circuit, by having their continuityinterrupted by the isolator, as described.

It will be understood that the parts indicated by the reference numeral 28 and hereinbefore referred. to as translating devices, may be used for a variety of purposes; but in order to show an application of the present invention, l. have selected as an illustrative case the one in which these translati ng d evices are in the form of electro-magnets forming parts of an automatiitvle hone exchange switching apparatus, whic apparatus, outside of said translating devices, is not Theouter trailer brush .40 is ca herein claimed as a part ofthe present inven- .tion;

Such automatic switchingapparatus as I have herein shown, for the purpose above stated, may comprise, among other parts, a clutch magnet '49 connected b conductors 48 in series with conductor 42, t e latter connecting to the inner ring 41 of the individual selector atone end and at the other to conductor 34 at point 42", (see Fig. 2). This magnet '49 is provided with a pivoted armature acting as a detent for the bell-crank lever 51.

A constantly rotating shaft 53 is provided with a ratchet 54 fast thereon, adapted to be 80 enga ed by a awl 52 carried by a disk 55 loose ymounte onthe shaft 52. The hooked end of the lever 52 has a tendency to engage a tooth of the ratchet wheel 54 under the influence of a spring 55. This, tendency is opposed by the engagement of the opposite rounded end of the lever 52 with the end of the bell-crank lever 51. The strength of the spring 55 is so proportioned that it will overcome the tension of a spring 51 which holds the lever 51 against its stop. Obviously as long as the lever 51 is held in its position of rest by the catch of the armature 50, the hooked end of the lever 52 cannot engage any of the teeth of the ratchet 54. But as soon as the lever 51'is released from engagement with the catch of armature 50, the spring 55 will overcome the tension of the spring 51; the hook of the lever 52 will enga e a tooth of the ratchet 54, and the latter eing fast on the constantly rotating shaft, will carry the lever 52 around with the same. The rounded end of lever 52, then breaks engagement with the end of the lever 51, whereupon thes-pring 51 will return the latter to its position of rest.

Secured to the disk 55 or to a sleeve carrying the same, is a cam 56. When the c-utch magnet 49 becomes energized, it attracts its armature 50, releases the bell crank lever 51 and the pawl 52 as above described. The latter engages wit-hone of the teeth of the ratchet 54 which then causes the rotation of the disk 55 and the cam 56. The impulses energizing the magnet 49 are of very short 5 duration, and the armature 50, therefore, is immediately released and engages and holds again the spring controlled bell crank 51.

After one revolution of the cam 56, the outer end of the pawl 52 strikes against the bell crank lever 51, becomes disengaged from the ratchet 54 and the disk 55 with the cam 56 is brought again to normal rest.

The cam 56 Figs. 3 and 4, is so arranged that it normally depresses a roller 57 secured to a rod 58, which latter is slidable in suitable bearings. Secured to the rod 55 is a lug which by means of a rope, wire or belt, is connected to a weight 60. The tendency of this weight is to lift the rod 58 but is normally 1 40 lifter, 61.

50 65 when that shuttle is not in use.

10 stop-lever plate 62-normall1y pressed forward by a spring 70. At one en of this stop-lever plate is a sto lug 62, which, under condi tions hereina ter described, is ada ted to engage the teeth of a stationary rac 64.

Located in a row in front of and substantially parallel to the stop lever. plate 62 are the terminal shuttles one for each subscribers line entering the switch-board. These terminal shuttles correspond in function to the horizontally movable terminal carriages of the exchange shown and described in U. S. Patent No. 686,892, herein before referred to and comprise each a metal sleeve 71 slidable vertically on a metal rod 68 and carrying a, '25 contact spring 65 in electrical connection therewith. Each of these contact springs has at its bottom end an outwardly turned toe to the bottom of which is secured a catch which latter is arranged to engage, under a e conditions hereinafter described, a detent 81 pivoted to the sleeve 71 and having an extension adapted to engage a sto 82.- of these shuttles carries also a ever 63 fulcrumed thereto, having each a curved upper end adapted to engage the stop-lever plate 62, under the tension of a sprin 69 also carried by the sleeve 71. Each 0 these levers 63 is also provided with a catch lug 63 for engagement with the -u turned ed e of the The lower en of each of t e levers 63 forms an armature for an electro magnet 28, there being one such magnet for each lever. These magnets constitute in this case the translating devices hereinbefore referred to.

- Arranged in .a row in front of the shuttles are a series of contacgsprings 66, each connected to a separate terminal cli 2 and each normally engaging the toe of a sl futtle spring Also arranged in a: row transversely of said shuttles are a plurality of superpos ed cord circuit terminal rods or busbars 67 forming the electrical connecting means between a calling and called subscribers shuttle.

In order to prevent more than one termi nal carria e spring 65 to make contact with a rod 67, t e armature lever 63 and the stoplever plate 62 operate as follows: The terminal rods 68 are all in one plane as also the upper ends of the armature levers 63. The 11 ter 61 and the stop-lever plate 62 are in the form of bars of-substantially the length of the entire row of terminal rods 68, and are capaillustrated in 3, of the drawings.

Each

ble of placing any one of the terminal shuttle springs into contact with any one of the rods 67 in the following manner: All armature levers 63 are normally resting against the front side of the stop-lever plate 62 as When an armature lever 63 is attracted by its electro-magnet 28, the upper 'end of the ever is removed from the front side of the stop lever plate 62 and this'plate in being lifted by the weight 60 will glide off the rest of the armature levers and fall forward onto the upper end of the attracted armature lever. Its stopping edge is thereby placed into the plane of the stopping teeth 64, is engaged by the lowermost of these teeth and the stop lever plate 62 will thereby be stop ed and the contact spring 65 of the termina shuttle be brought in contact with the first bar 67, all of which takes place during one complete revolution of the cam 56. In case a second shuttle should be displaced, its armature would be attracted by its magnet 28, and when the stop plate '62 is'lifted, it will not glide oii the 'rest'of the armature levers and fall forward onto the upper end of the attracted armature lever, but would rest against the u er end of the armature lever of the already lsplaced shuttle from which it would glide off in the further lifting process and its stopping edge placed into the lane of the stopping teeth 64 where it woul be engaged by the second stopping tooth and made to stop so that the contact s ring 65 of the second terminal shuttle is brought in contact with the second bar67. This mode of operation is repeated with every shuttleuntil a shuttle has been connected to each of the rods 67 The devices for resetting the terminal carriages are illustrated in Figs. 3 and 4, and consist of insulated resetting. plungers 80, one for each cord-circuit bar 67, and a detent 81 on each terminal carriage. -When the plunger 80 has pushed back the spring 65,

the latter is engaged by the detent 81 the terminal carriage drops by gravity and when it reaches its position of rest, the'rear end of the detent 81 strikes the pin 82, and the detent releases again the spring 65, so

that when the terminal carriage is lifted, it may againenga e with one of the cord.c1r

cuit terminal ro s 67. The plunger 80 ma beoperated by any suitable means. Sue

means however, is beyond the scope of the present invention. T e stops. 15 and 32 are set by rotating the rings 18 and-33by means of levers attached to thelugs 76 and 79.

'Any suitable. means for giving reciprocating motion at the proper tune to these levers may be employed. .The peri hery of the rings 18 and33 is provided wit lugs 74 and 77, one for each stop 15 and 32, engaging the fingers 75 and 78 on those stops. The detents 14 and '31 under the tension of suitable spring engage again the stops 15 and 32, and retain the same, so that the trailer arms 21 and 38 may resume their normal rotation.

Operation: When in the operation of this apparatus ground is placed on the sender 1 o a subscribers station and the number of thecalling line is, for instance, No. 49, as illustrated in the drawings, a circuit is established as follows :from ground at the sending station over the line to the central station, to one of the springs 66, over conductor 73 to the first isolator clip 2 of the fifth group from the left hand side of the groups of isolator clips, illustrated in Fig. 1, from the isolator blade 7 normally in contact with all the clips ofthe group, to the lower clip 4 of this group, one of the conductors 5 'to one of the group selector magnets 13, to the battery ring 17 of the group selector, over the conductor 45 to the main switch 35, through the better 36, and to ground at the central station. he effect of this current will be the energization of the magnet 13 representing thegroup containing the lines No. to 49 which in attracting its armature 14 removes the detent from the stop 15 and allows the latter to fall inward into the path-of the outer end of the trailer arm 21' of the group selector.

When the stop 15 is released by the detent on the armature .14, it closes a circuit asfollows :-fro'm ,ground at the central station to the isolator imagnet 1], see Fig. 1, over conductor 12 to the outer battery ring 18 of the group selector, the back contact 16 of the stop :15, the stop 15 to the inner battery ring 17,-ove:=" conductor to main switch 35, see Fig. 2

V of the drawings, through battery 36 to ground. The energization of the magnet 11 by this current results in the attraction of its armature 10, the removal of the detent of this armature from-the bell crank 8,

, the vertical arm of which under. the tension of the 5 ring 9 moves toward the left, see

Fig. 10 the drawings, and removes the isolator blades 7 from the roups of isolator clips 2, making it imposslble, for the time being, for any one-to send in a call into the central apparatus. The normally rotating trailer arm 21 is now stopped'by one of the,

,lows:fro1n ground at the sender 1 to the individual clip No. 49, that is the uppermost cli in the fifth row from the left hand side of Fig; 1 of the drawings, one of the conductors 3 to the tenth contact point 19 ofthe group selector, the trailer-brush of the outer series 23 now in contact therewith, the second trailer brush of the Inner serles 24 of brush .8 of the trailer arm 21 resting upon the outermost of the rings 25, one of the conductors 29 to one of the magnets 30 of the individual selector, and representing the unit digit of the callin No; 49, to the battery ring 33 of this se ector, the conductor 34 to the main'switch 35 and through battery 36 to ground. The eiiect of this current is to attract the armature 31 of the magnet 30, remove its detent from the stop 32 which thereby drops into the path of the outer end of the trailer arm 38 of the individual'selectpr, and causes the same to'interrupt its revolution and to stop with its trailer brush 40 onthe contact point 43 representing the number 9 and with its inner brush on the battery ring 41. A circuit has now been established as followsz from theleft hand side of the battery 36, Fig. 2 of the drawings, to the left bar of the main switch 35, conductor 34, conductor 42, wirejoint 42' to the batter ring 41 of the individual selector, the trai er brush 39of the trailer arm 38, the outer trailer brush 40, one of the contact points 43 one of the conductors 44, to oneof the individual translating devices or'electromagnets- 28 in the actuator, and

magnet 28- of the th, roup from below, on the right hand side of vig. 2 of the drawingls, t e

'over one of the conductors 27, to one of of the trailer brushes of the inner series 24 of brushes of the trailer arm 21 resting upon the rin 46, the conductor 47' to the right hand'b ade of the'main switch 35 and to the right hand side of the battery 36.- The e ect of this current in the present case is to actuate the translating device 28. Having illustrated the translating device in the presentcase as an'electro-ma net, it will result in the energization of t llS electromagnet 28, re )resenting .the calling or sending station 0. 49.

Simultaneously with the energi'zation of the magnet No. 49 of the groups of translating devices or electro-magnets 28, the clutch magnet 49 .which is connected to the conductor 42 by means of the conductors 48, is energized, has attracted its armature 50 and has released the detent 51, whereby the pawl 52 is also released and drops into one of-the teeth of the ratchet 54. The ratchet'54 is secured to the shaft 53 constantly rotating with it. Thedropping of the awl 52 into one of the teeth of the constant y rotatingratchet 54 results in one complete, revolution of the cam 56 and in an up and down movement of the rod 58 under the pull of the weight 60 as hereinbefore described. One of the magnets 28 having been. energized and having attracted its armature lever 63, the upward movement of the-rod 58 and the in-the chosen exam 1e to the lowest electrolifter 61 will cause the breaking of the connection between the stationary spring 66 and the spring 65 of the terminal-carriage of the calling line and will bring this terminal carriage into contact with one of the idle cord circuit bar s or rods 67 determined by the shoulder 83 of the stop" lever 62 which prevents the stop. lever to tilt forward until the bent upper ends of priorly displaced armature levers 63 are passed. 7

What is claimed as new and useful and desired to be secured by Letters Patent of the United States is 1. A progressive contact-maker comprising contact points divided into groups or sets, a normally rotating, trailer-arm adapted to make contact with multiple contact points of one group at one time, means for interrupting the rotation of the trailer arm, and means for controlling the interrupting means.

2. A progressivecontact maker comprising contact points divided into groups or sets, a plurality of groups of circuits in which said contacts are connected, a normally rotating trailer-arm adapted to make contact with the contact points of one'group at one time, means for interrupting the rotation of the trailer arm, and means, independent of the circuits containing the contact points, for controlling the interrupting means.

3. The combination with a series of lines, of a terminal clip for each of the lines,a contact point for each of the terminal clips,both clips and points being divided into groups or sets, of a normally rotating contact-maker adapted to. make contact with the contact points of one group or set at one time, by the relative movement between said contact maker and points, means for interrupting the rotation of the contact maker, and means controlled by the lines for operating the interrupting means.

4. Thecombination with a series'of lines, of a terminal clip for each of the lines, a contact point for each of the'terminal clips, both clips and points being divided into groups or sets, of a contact maker adapted to make contact with the contact points of one group or set at one time, by the relative movement between. said contact maker and points, means for temporarily holding said contact maker on said contact points, and means, controlled by the lines and independent of the circuit containing the contact points, for controlling said holding means.

5. The combination with a series of line terminals arranged in groups or sets, electromagnetic means for each group of line terminals, a normally rotating contact-maker adapted to establish electrical connection with said group of terminals, and means for stopping said contact maker, said means being controlled by said electro -magnetic means.

6. In an electrical system, means for selee-ting and identifying any one of a plurality branches extending between them less'in number than the total number ofcircuits to be served, each element of the first set adapted when actuated to select and connect to the extensions all of its group of circuits, and each element of the second set adapted when actuated to select and render operative a single unit out of the group, corresponding to. the circuit to be selected. p 7. In an electrical system, means for selecting and identifying any one of a plurality of circuits which consists of a rotatin circuit changer, a lurality of sets'of control ing elements, wit extension circuits or branches extending between them less in number than the total number of circuits to be served,

each element of the first set adapted when actuated to cause the circuit changer to select and connect to the extensions all of its group of circuits, and each element of the second set adapted when actuated to select and render operative a single unit out of the group, corrseponding to the circuit to be selected.

8. The combination with a series of line terminals divided into groups or sets and a series of normally open local circuits, one for each line terminal, of means controlled by the groups adapted to partially close one of said local circuits, and means controlled by one com onent in this group for completing said local circuit. 1 1 Y 9. In an electrical system of COIDIIIUIIICH: tion, the combination of the following instrumentalities: a central station, a plurality of sending apparatuses, line circuits connecting the same to the central station, and a circuit changing device at the central station comprising primary and secondary controlling means, together with branch circuit connections between the same and from the circuit changer to line identifying circuits, said primary controlling means adapted in response to a call over an individual line to render inoperative an inactive portion of the line circuits, and the secondary controlling means adapted to render inoperative an inactive portion of the remaining circuits, and to complete the connection to its identifying circuit.

10. In an electrical system of communication, the combination of the following instrumentalities: a central station, a plurality of sending apparatuses, line circuits connecting the same to the central station, and a circuit changing device at the central station com, prising primary and secondary controlling means, together with branch circuit connections between the same and from the circuit changer to line identifying circuits, said primary controlling means ada ted in response to a call over an individual line to 15 than the number of lines extending between render inoperative all the line and branch circuits except the group containing the calling line, and the secondary controlling means adapted to render inoperative all of the circuits of the group except the one calling, and

to complete the connection to its identifying circuit.

11. In an electrical system of communication, the'combination of the following instrumentalities: a central station, a plurality of substations with circuit contro ingdevices, line circuits interconnecting them, a circuit changing deviceat the central station compfisinglprimaryand secondary elements, and ranc extension circuits less in number said elements, said line circuits divided into groups, and having corresponding group contacts in the said rimary element, a controlling magnet for t e primary element for each groulp, adapted to beenergized over any line in t e grou controlling magnets for the secondary e ement, one corres onding to each unit in a single group in t e primary element, means to segregate the individual lines upon the operation of the circuit changing device, and ne identifying or controlling means associated with said clrcuit changing device and adapted to be selectively operated circuits of its respective group, a switching device controlled by said circuit-controlling devices to partially close all the branch cir- 4 0 cuits of the respective groups, one or more secondary circult closing devices adapted to complete y close any one of the branch .cir- 'cuits' partially closed, and a circuit interrupter ada ted to place all the primary circuit-controlling devices beyond the control of the said plurality of electrical circuits.

In testimony whereof I have hereunto set I my hand at New York, in the, county and State of New York "this thirtieth day of March, nineteen hundred and four.

ERNEST A. FALLER.

In presence of Monsn SIDON,

E. Li'mnns. 

